Below are couple of notes based on what we figured out today with Diego.
Why do we have *clean_db "das_db"* here?  couldn't this have some strange consequences?
* clean_db do **NOT check schema-stamp**, i.e.  on every mongodb restart, it drops das&parser. these databases seem to be created from DAS webserver (as not present in mongodb/manage scripts). is this intended behaviour?
  - imagine the scenario where mongodb is restarted and das still running. is it OK if das&parser is deleted? where are they used and when are they recreated?
* clean_db runs the js scripts only if the relevant collection file is present, while in [das/deploy#L38](https://github.com/dmwm/deployment/blob/cb516c1642502a854d2cfe489e40e5b9481b5716/das/deploy#L38) clean_das_db.js drops both parser and das. i.e. if das.ns file is not present it will not drop parser.